The study says losing 10 pounds every now and then and gaining it back can significantly increase your risk of heart-disease related death and heart attacks.

“We found that those with normal weight were the highest at risk for both sudden cardiac death and coronary heart disease death,” says Dr. Somwail Rasla, lead author of the study and internal medicine resident at Memorial Hospital of Rhode Island at Brown University.

The research examined data from more than 158,000 women over age 50, who self-reported their weight history. The women were either categorized as normal weight, overweight or obese, and were tracked over an 11-year period.

Women who were considered normal weight at the study’s start, but who reported a history of “weight cycling” — defined as losing more than 10 pounds and gaining it back at least four times, excluding sickness and pregnancy —had a 3.5 times greater risk for sudden cardiac death than women whose weights remained more stable. They also had a 66 per cent increased risk of dying from coronary heart disease.

Notably, this weight cycling didn’t increase these risks for women who were already overweight or obese.

Rasla has a theory as to why normal-weight women are more likely to experience health problems with yo-yo dieting than their overweight counterparts. (Other research has also shown that normal-weight women are more likely to die from with heart failure than obese women.)

“Obese people have higher blood pressure, high diabetes but over a long period of time, and it’s been found that their bodies develop a compensatory adaptive mechanism to different diseases,” he says.

Even semi-dramatic weight changes can have extremely negative effects on the body; every time your weight fluctuates, so does your heart rate, blood pressure, cholesterol and blood glucose levels. Whenever the weight-loss/weight-gain cycle is repeated, these basic metabolic processes are less likely to return to healthy, baseline levels.

Additionally, gaining and losing weight over and over again can trigger insulin resistance, increasing your risk of diabetes and heart disease. Not good.

Nonetheless, Rasla is quick to advise overweight or obese women who are trying to lose weight shouldn’t give up for fear of the consequences of weight cycling.

“However, the study adds to the literature that weight cycling in normal weight people may have adverse effects on their health,” he says, “and this should be taken with caution. The better way is to keep your weight still.”

You heard it here first, ladies: Yo-yo is a no no. All the more reason to eat right, exercise, and — most importantly — love the skin you’re in.